The present invention relates to a new and improved construction of a seeker, particularly for target seeking missiles.
In its more specific aspects, the invention relates to a new and improved construction of a seeker, particularly for target seeking missiles, including an imaging optical system which is universally movably supported with respect to a structure by means of a gimbal mount via an inner gimbal and an outer gimbal, and a detector at which an image of the field of view can be produced by means of the optical system. In such seeker,
(a) the imaging optical system comprises an optical member which is arranged at the inner gimbal on the side of the object and which defines an optical axis of the imaging optical system, PA0 (b) the imaging optical system includes a deflecting mirror which is disposed at the inner gimbal and which folds a path of rays defined by the imaging optical system, and PA0 (c) reflecting means are provided and reverse the path of rays. PA0 the deflecting mirror is fixedly arranged at the inner gimbal and on the object side of the reflecting means such that the deflected optical axis coincides with the gimbal axis of the inner gimbal, PA0 the detector is retained in the outer gimbal on the gimbal axis of the inner gimbal, and PA0 the reflecting means is also arranged on the gimbal axis of the inner gimbal and reverses the deflected path of rays which is deflected by the deflecting mirror in the direction of the gimbal axis of the inner gimbal and towards the detector.
In a known seeker, an infrared receiving system conjointly with a rotational speed sensor and the associated controlling and amplifying electronics are rigidly interconnected in a housing. The infrared receiving system therein comprises a gas-cooled multi-element detector, an imaging optical system in the form of a folded lens system and a scanning device for scanning a field of view covered by the seeker. The imaging optical system images the field of view in a plane defined by the detector. The scanning device causes the image of the field of view to be moved relative to the detector such that the multi-element detector scans the field of view.
The aforementioned housing defines a rotatable gimbal of a gimbal system and such rotatable gimbal is rotatable about the pitch axis and the yaw axis. The seeker, therefore, can be rotated relative to a structure like, for example, the airframe of the missile, through a limited angular range and thereby is aimed at a target. During such rotation through the limited angular range, the electrical conductors of the multi-element detector as well as the high-pressure gas infeed conduits must be flexibly guided across the two gimbal axes, namely the pitch axis and the yaw axis. Such arrangement is constructionally and spatially expensive. The seeker head becomes undesirably large in size and heavy in weight. Furthermore, there result unduly high gimbal moments of inertia.
There are further known seekers in which the imaging optical system is arranged at a gimbal which is supported for movement about two axes whereas the infrared detector is structurally fixedly mounted. The focused beams of infrared rays are passed through the gimbal axes using additional optical elements, namely lens systems and mirrors, and intermediate images. An infrared image is thus produced in the structurally fixed plane of the infrared detector. This requires a very complicated and expensive imaging optical system. Moreover, transmission losses and scattering losses will additionally occur at the optical elements in such construction particularly in the infrared region. Furthermore, losses are incurred in image resolution.
In a seeker such as described, for example, in German Published Patent No. 2,454,480, published on Dec. 11, 1975, an outer gimbal is arranged for rotation about the lengthwise axis of the missile. An inner gimbal can be rotated relative to the outer gimbal about an axis which extends perpendicular to the gimbal axis of the outer gimbal. The inner gimbal supports a lens system which defines an optical axis, and further supports a deflecting mirror and an image rotating ridge mirror. In this construction, the path of rays extends from the lens system to the ridge mirror and therefrom to the deflecting mirror. The deflecting mirror can be swivelled about the gimbal axis of the inner gimbal by means of a gearing. The swivelling movement is effected through half of the rotational angle of the inner gimbal. In this manner, the path of rays is constantly directed into an optical system which is fixed with respect to the outer gimbal and which guides the light beam to a detector.
A further seeker such as known, for example, from German Published Patent No. 2,637,735, published on Apr. 5, 1979, includes scanning means for scanning a field of view by means of a detector using a rotating facetted mirror. The seeker head comprises an outer gimbal and an inner gimbal. A stabilizing gyro rotor is supported at the inner gimbal and carries an annular facetted mirror. A lens system is seated at the inner gimbal and defines an optical axis. A deflecting mirror disposed at the inner gimbal deflects the path of rays laterally obliquely to the facetted mirror from which the imaging light beam is directed to the detector, which is fixed with respect to the inner gimbal, via further optical members.